This invention relates generally to RF tunable circuits and is particularly directed to a low cost, wideband UHF oscillator circuit.
Leadless electronic components are gaining increased acceptance because of their small size and the ease with which they are automatically positioned in circuit by robotic component handling apparatus. The smaller size of these surface mounted, or "chip", components reduces circuit space requirements and relaxes thermal dissipation criteria. Electrical coupling of the ends of the leadless components to isolated conductive portions of a printed circuit (PC) board by soldering eliminates the precise positioning required in inserting component leads through apertures in the PC board as in the case of conventional discrete components. Automatic, high speed positioning of these surface mounted components eliminates the labor intensive mounting procedure associated with electronic components having leads, thus, substantially reducing the cost of PC board fabrication.
These surface mounted components, however, suffer from operating limitations in certain circuit applications. For example, chip capacitors inherently have a lower Q value than the more conventional type of capacitor with leads. In a tuned circuit this reduced Q value is frequently undesirable because of limitations in the bandwidth over which the circuit may be tuned. Thus, the advantages of surface mounted components in terms of reduced size and heat generation as well as ease of mounting and connecting in circuit in an RF receiver are frequently outweighed by their inherent operating limitations in a variably tuned circuit.
The present invention resolves the aforementioned problems encountered in the prior art by providing a UHF oscillator circuit comprised almost entirely of surface mounted devices which is capable of being tuned over a frequency range in excess of an octave.